1. Field of the Invention
The present invention relates to a wire-wound coil including a wire that is wound around a winding core with wire ends connected to electrodes provided on flanges and to a method for manufacturing the wire-wound coil.
2. Description of the Related Art
FIG. 16 is a perspective view of a known wire-wound coil. FIG. 17 is a side view of a known wire-wound coil in which the coating agent has entered and accumulated in rounded corners R.
As illustrated in FIG. 16, the wire-wound coil includes a core 100 having a winding core 102 around which a wire 101 is wound and flanges 103. The ends of the wire 101 are connected to electrodes 104 provided on peripheral walls of the flanges 103. A portion is removed from each of the flanges 103 to form rounded corners R 103a. 
In the above-described core 100, a space is created between the end portion 101a of the wire 101 and the rounded corner R 103a of the flange 103, and a coating agent C used for coating the wire-wound coil accumulates in this space, as illustrated in FIG. 17A. If the coating agent C accumulated in this space contracts due to a temperature change, end portions 101a of the wire 101 are pulled towards the surface of the flanges 103 by the contracted coating agent C, as described in FIG. 17B. This may cause the wire 101 to break. Similarly, the wire 101 may break because of expansion of the coating agent C.
A known wire-wound coil that prevents the wire 101 from breaking due to contraction and expansion of the coating agent C by inhibiting the entry and accumulation of the coating agent C into the area around the end portions 101a of the wire 101 is disclosed in Japanese Unexamined Patent Application Publication No. 2003-151837.
FIG. 18 is a side view of a known wire-wound coil having a structure for preventing breakage of the wire. As illustrated in FIG. 18, inclined surfaces 103b are provided on the flanges 103 of the core 100 of the known wire-wound coil. The end portions 101a of the wire 101 are arranged along the inclined surfaces 103b such that the tips are connected to the electrodes 104.
In this manner, the space between the end portion 101a and the flanges 103 is eliminated. Consequently, the entry and accumulation of the coating agent C into the area around the end portions 101a of the wire 101 is eliminated so as to prevent breakage of the wire 101 due to contraction and expansion of the coating agent C.
Similar wire-wound coils in which the end portions of the wire are disposed along the sidewalls of the flanges to prevent breaking of the wire are disclosed in Japanese Unexamined Patent Application Publication Nos. 2002-329618, 2002-170717, and 2003-243221.
However, the above-described known wire-wound coils have the problems described below.
FIGS. 19A and 19B are side views of a wire-wound coil wherein a coating agent has entered and accumulated between the wire-wound coil and a substrate.
As illustrated in FIG. 19A, a space is created between the lower side of the known wire-wound coil and a substrate 200. Therefore, when the wire-wound coil is coated, the coating agent C tends to enter and accumulate in this space. If the coating agent C accumulates in this space, the end portions 101a of the wire 101 are pulled toward the substrate 200 when the coating agent C contracts and, consequently, the end portions 101a of the wire 101 break, as illustrated in FIG. 19B.
If the wire-wound coil is a wire-wound coil using two wires, such as a common mode choke coil, the flanges 103 have to be divided such that the two wires can be connected to electrodes 104a and 104b, as illustrated in FIG. 20. To completely separate the electrodes 104a and 104b, a groove B is provided between the electrodes 104a and 104b. End portions 101a-1 and 101a-2 of the two wires are disposed along inclined surfaces 103b-1 and 103b-2, respectively, and connected to the electrodes 104a and 104b, respectively. For this wire-wound coil, the coating agent C may enter and accumulate in the groove B and cause the end portions 101a-1 and 101a-2 to break when contraction or expansion of the coating agent C occurs.
This problem cannot be solved even when a wire-wound coil according to Japanese Unexamined Patent Application Publication Nos. 2002-329618, 2002-170717, and 2003-243221 is used.